There are known methods of producing non-perfluoroelastomers or aqueous fluororesin dispersions by emulsion polymerization using perfluorohexanoic acid (C5F11COOH) or a salt thereof.
Patent Literature 1 discloses a method for producing a fluoroelastomer including emulsion-copolymerizing vinylidene fluoride and a fluoroolefin monomer other than the vinylidene fluoride in the presence of an emulsifier represented by C5F11COOM, wherein M is H, NH4, or an alkali metal.
Patent Literature 2 discloses that a tetrafluoroethylene/propylene copolymer latex is produced by emulsion polymerization using CF3(CF2)4COO−(NH4)+ as an emulsifier (see Reference Example 5).
Patent Literature 3 discloses a method for producing a fluoropolymer including emulsion-polymerizing a fluoromonomer in the presence of a polymerization catalyst in an aqueous medium containing a fluorocarboxylic acid compound, wherein the aqueous medium during the polymerization has a pH of at most 4. The examples of this document disclose that tetrafluoroethylene is emulsion-polymerized in the presence of C5F11COOH to provide a polytetrafluoroethylene aqueous emulsion.